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Valve Adjust Shim Material?

"I'm sure it's a source of deep pain and perpetual regret at the Maserati factory that they didn't have your resumes in hand at the time so the design work could have been done the right way and the subsequent owners could now have completely trouble free machines."

I'd be surprised if 90% of the engineers at Maserati didn't know that design was shit the day it left the drawing board. Anyone who's worked in a factory knows that all too often the final design is one influenced by timelines, budgets, NIH, and the old downfall - pride. We can argue all day about resumes but there's no arguing that design has no place in a production vehicle. It might be OK for a race engine (?) that will be expertly assembled and doesn't need to last long or see a wide variety of service conditions.

The proof is in the pudding.....
 
Not to mention that DeTomaso wanted a more affordable line of cars and available on a very short time frame.

Yeah, the weaknesses and issues are pretty well known.
 
Have made literal hundreds of this type of shim over the years...
Some bought, others not when the size or adjustment range dictated other..
If making i use S-7......
Buy the OD at size. Cut off blanks at same length. Hold in a collet on the lathe w/stop and plunge the valve stem socket using an end mill ground with 0* face relief ,held in the cross slide, plunge to needed depth, send to heat treat....Finish when returned on the valve grinder to clean the tops to finished thickness.
I always pointed a small center point in the bottom of the valve socket to be sure that the bearing area was flat.

Cheers Ross
 
The sealant I used in several locations was the factory Porsche case sealant used in 911's. It's a loktite product but sold only through Porsche. My spelling is probably OFF as it's German- Flachendictung. It's an orange colored anaerobic sealant. I found it increased the longevity of the teflon sealing rings at the bottom of the cylinder barrels also. These extremely thin pieces of teflon, needed as much help as they could get. Once they deteriorated, the engine coolant would go into the oil pan. Case sealant 574.

I always removed the filters in the head, and then drilled the oil restrictor a little larger. the filters in the head was just DUMB considering most people didn't practice a cool down period for their turbos, and the oil just cooked. There WAS an aftermarket kit that had external oil lines go up the back of the engine to oil the cams, but I thought the liability of installing them just wasn't worth it. Once I realized my fixes could make the engine last 100K miles, with WAY more than that if run by a person that realized just how important it was to do oil changes.

These cars may draw disdain from a lot of people, but their competition was BMW, which they just blew away. These cars were incredibly fast, the interiors seemed pretty luxurious. I think to own one now in 2022, you'd have to be a masochist. There's just so many parts that can fail that MUST be working correctly for the car to perform.

Instead of MAKING valve shims, just grind down the ones you have. The exhaust valves are usually the one that get tight, and grinding off a few thousandths is nothing. I used my Sioux valve grinder, but not on the side to do the seats, but the right side that was designed to grind the top of the valve stems. With micrometer feed, super easy to take off a few thousandths.
 
Thanks, Brian
I had already replaced the Teflon gaskets with the O-rings the factory changed to at some point. From the looks of the ones I removed, the plastic just extruded with time and pressure. And yes, this one had coolant in the sump when I acquired it some years ago.
 
the lash caps for my titanium valves were 59 hrc and had a ra of 0.1µ last time i looked. the tolerance can be 10-25µ, i would assume depending on whether they are supposed to rotate. they can be domed or flat, in your application i would assume domed. my valves had very sharp corners. will you make them with a relieve inside? the suface finish is not trivial from a tribological standpoind, ra being just one parameter. some have a dlc coating. i strongly doubt some run of the mill steel is suitable for these intricate parts (→vim-var/esr, superclean). i also think o1 has too much carbon.

i dont say this often, but i would never consider making them myself, especially if available for $7. anyway, dont forget the holes and radius the edges.
 
i dont say this often, but i would never consider making them myself, especially if available for $7. anyway, dont forget the holes and radius the edges.
Dian, I'm not sure what you mean by "don't forget the holes".

They're available in 95 sizes from 2.10 to 4.475 mm so buying a set of only one each is an investment. In fact, the ones required for an individual setup are likely in a smaller range but you'd still want two or three of a size to meet the setup needs. If I knew exactly which ones is a much smaller set but the other peculiarity (liability) is that there's a gasket between the head and cam box, the thickness of which changes the lash so it's sort of an equation with more than one variable.
 
You don't need to buy a set. If you can't afford to measure the lash and order the correct ones you need - then it sounds like you need this high-zoot car to drive to work and can't afford the down-time. If so you don't need a full set of valve shims, yo need a Corolla. Which BTW has an engine that goes 300k miles with no special valve shims needed.
 
yo need a Corolla. Which BTW has an engine that goes 300k miles with no special valve shims needed.
OTOH, there was the 3.4-liter V6 engine that Toyota dubbed the “5VZ-FE” was stuffed into nearly every US-market Tacoma and 4Runner they produced between 1995 and 2004; it has the shim-over-bucket valvetrain design being discussed here. The dealer gave a free valve adjustment at 1000 miles, but it needs another one every 30,000 miles, for which they are now charging $1250, because it requires disassembling the entire top end of the engine, so few owners ever had it done and then many of them worked hard eat the valves before 100,000 miles.

jack vines
 
Holy heck man - don't spend the money on stuff you don't need, life's too short to be making stuff you can just buy. Measure the lash, if it it's too tight just buy the ones you need. While the cars off the road polish the spokes or detail the interior or something. The only bike I have with valve shims, every time I check it's dead nuts middle of the tolerance band.

Corolla - shims or locknut adjusters - damn I honestly don't know!
 
There is no way any jap car would use a bodge like that........because they are keen on semi hemi and pent heads with two overhead cams.....and reliability......the diagram shows a completely bankrupt scheme to stick two exhaust valves where one used to be,without spending ten more lira they didnt have.
 
These cars (Maserati Biturbo) may draw disdain from a lot of people, but their competition was BMW, which they just blew away. These cars were incredibly fast, the interiors seemed pretty luxurious. I think to own one now in 2022, you'd have to be a masochist. There's just so many parts that can fail that MUST be working correctly for the car to perform.
For true and from the expert. If anyone tries to give you a BiT, hit him with a brick, bury his body and push the car off a cliff. Your chances of getting away with it are better than the chances of keeping the BiT running.

jack vines
 
"Dian, I'm not sure what you mean by "don't forget the holes":

i assume they need central holes so the oil can get in there.
 
"Dian, I'm not sure what you mean by "don't forget the holes":

i assume they need central holes so the oil can get in there.
I don't know what you're thinking of. This is a small thimble about the size of the end of your little finger that someone has posted a picture of earlier. It's a reasonably close fit over the stem of the valve and never moves relative to the stem so oil entry isn't functional.
 
Lots of motors use valve stem caps like the drawing,so that the ends of valve stems dont need to be hard......two Ive used recently are the Ford diesel truck motors,and the 1970s John Deere tractor motors.
 
One of the cleverest systems Ive seen was used in the 1960s Caterpillar 1674 truck and scraper engines .....the 1674 was a quadcam V8 with 4 valves per cylinder,and it had a very clever system to automatically adjust valve stem clearances by using a sort of loose ratchet on each valve......twenty years later Kawasaki copied the system exactly on its high powered 4 cyl motorbikes. .
 
I don't know what you're thinking of. This is a small thimble about the size of the end of your little finger that someone has posted a picture of earlier. It's a reasonably close fit over the stem of the valve and never moves relative to the stem so oil entry isn't functional.
some definitely do have central holes, because they rotate.
 
OTOH, there was the 3.4-liter V6 engine that Toyota dubbed the “5VZ-FE” was stuffed into nearly every US-market Tacoma and 4Runner they produced between 1995 and 2004; it has the shim-over-bucket valvetrain design being discussed here. The dealer gave a free valve adjustment at 1000 miles, but it needs another one every 30,000 miles, for which they are now charging $1250, because it requires disassembling the entire top end of the engine, so few owners ever had it done and then many of them worked hard eat the valves before 100,000 miles.

jack vines
Look again, that engine has nothing like this ball of stupidity

The Toyota is a straight bucket follower

IME you adjust shimmed bucket valves once a few thousand after doing the head. Then they are good, absent stupidity, practically forever.

There are so many ways for this nightmare to go wrong it is hard to imagine why.
basically an engineer decided they could open 2 valves with one follower and that was that

stupid.

IF there is any wear in that follower, how to you know what the clearance is? will it be the same tomorrow?
what happens when on valve moves more than the other?
 








 
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